Three Roll Pass Units

Nowadays, groove rolling in stands with 3 rolls aligned in 120° angle gain more and more importance, especially for round rods and tubes. PyRolL supports the simulation of three-roll rolling stands via the ThreeRollPass class. The ThreeRollPass is derived from RollPass, so hook functions defined for RollPass also apply for three-roll passes, although they may not always be appropriate, but many are. Always pay attention when simulating three-roll passes, that appropriate models are use, or the results may be heavily incorrect, which is not guaranteed to throw an error.

The main difference is that the dimensions of a three-roll pass are not right-angled, due to the 3-fold symmetry. As the figure shows, the width and height are under an angle of odd multiples of 60°. The caveat is, that width and height can not directly be measured here, but only their half. This measure is implemented as hook functions for profiles featuring the type "3fold" (see Profile Classifiers for further information).

The width of ideal filling of the roll pass is here also dependent on the roll gap, as it is not for two-roll passes. The width of ideal filling \(w_{i=1}\) is given by the equation below, with the usable width of the groove \(w_\mathrm{u}\) and the roll gap \(s\). As for two-roll passes the pass is always ideally filled, if no spreading resp. material flow model is loaded.

\[ w_{i=1} = \frac{w_\mathrm{u}}{\cos 30°} + s \tan 30° \]

Dimensions of Three-Roll Passes

For definition of a three-roll pass the same groove and roll objects as for two-roll passes are used. The magic happens in ThreeRollPass.Roll after creation of the instance. So defining three-roll passes is straightforward. Roll gap means the height of the clearing between the roll faces outside the actual groove hole, similar to two-roll passes.

ThreeRollPass(
    label="My Three-Roll Pass",
    roll=Roll(
        groove=CircularOvalGroove(
            depth=8e-3,
            r1=6e-3,
            r2=40e-3
        ),
        nominal_radius=160e-3,
        rotational_frequency=1
    ),
    gap=2e-3,
),

Profiles originating from three-roll passes are marked with the special type classifier "3fold" (see Profile Classifiers), which indicated that the profile has a 3-fold symmetry instead of the common 2-fold symmetry of two-roll produced profiles.

class ThreeRollPass(roll: Roll, label: str = '', **kwargs)

Represents a roll pass with three working rolls and 3-fold symmetry.

Parameters:

roll – the roll object representing the equal working rolls of the pass
label – label for human identification
kwargs – additional hook values as keyword arguments to set explicitly

class DiskElement(parent: Unit, index: int, **kwargs)

Represents a disk element in a roll pass.

Parameters:

label – label for human identification
kwargs – additional hook values as keyword arguments to set explicitly

abs_draught: Absolute draught (change in height).

abs_elongation: Absolute elongation (change in length).

abs_spread: Absolute spread (change in width).

contact_area: Area of contact of the workpiece to the rolls.

deformation_resistance: Equivalent deformation resistance (mean flow stress increased by deformation efficiency).

draught: Coefficient of draught (change in height).

duration: Time needed to pass the unit (temporal extent).

elongation: Coefficient of elongation (change in length).

energy_consumption: Energy consumption of this unit per produced mass.

free_surface_area: Area of free surface.

iteration_precision: Precision of iteration break in solution loop.

length: The length of the unit (spacial extent in rolling direction).

log_draught: Log. coefficient of draught (change in height).

log_elongation: Log. coefficient of elongation (change in length).

log_spread: Log. coefficient of spread (change in width).

mass_flux: Flux/throughput of mass through this unit.

max_iteration_count: Count of maximum solution loop iterations before aborting.

power: Total energy demand per time of this unit.

rel_draught: Relative draught (change in height).

rel_elongation: Relative elongation (change in length).

rel_spread: Relative spread (change in width).

property roll_pass: ThreeRollPass: Reference to the roll pass. Alias for self.parent.

spread: Coefficient of spread (change in width).

strain: Mean equivalent strain applied to the workpiece.

strain_rate: Mean equivalent strain rate.

surface_area: Surface area of workpiece within the unit.

velocity: Mean velocity of material flow.

volume: Volume of workpiece material within the unit.

volume_flux: Flux/throughput of volume through this unit.

abs_draught: Absolute draught (change in height).

abs_elongation: Absolute elongation (change in length).

abs_spread: Absolute spread (change in width).

back_tension: Back tension acting on the current roll pass.

property classifiers: A tuple of keywords to specify the shape type classifiers of this roll pass. Shortcut to self.groove.classifiers.

contact_area: Area of contact of the workpiece to the rolls.

property contour_lines: List[LineString]: List of line strings bounding the roll pass at the high point.

deformation_resistance: Equivalent deformation resistance (mean flow stress increased by deformation efficiency).

disk_element_count: Number of intermediate profiles to create during unit solution (in and out profiles are not counted within).

property disk_elements: List[DiskElement]: A list of disk elements used to subdivide this unit.

displaced_cross_section: Cross-section of the roll pass witch is displaced due to elongation and won’t reappear in the next roll-pass.

draught: Coefficient of draught (change in height).

duration: Time needed to pass the unit (temporal extent).

elongation: Coefficient of elongation (change in length).

elongation_efficiency: Efficiency of a roll pass to elongate a incoming profile.

energy_consumption: Energy consumption of this unit per produced mass.

entry_angle: Angle at which the material enters the roll gap.

entry_point: Point where the material enters the roll gap.

exit_angle: Angle at which the material exits the roll gap.

exit_point: Point where the material exits the roll gap.

forward_slip_ratio: Ratio of forward slip of the roll gap.

free_surface_area: Area of free surface.

front_tension: Front tension acting on the current roll pass.

gap: Gap between the rolls (outer surface).

height: Maximum height of the roll pass.

inscribed_circle_diameter: Diameter of inscribed circle between roll barrels as alternative to roll gap definition.

iteration_precision: Precision of iteration break in solution loop.

length: The length of the unit (spacial extent in rolling direction).

log_draught: Log. coefficient of draught (change in height).

log_elongation: Log. coefficient of elongation (change in length).

log_spread: Log. coefficient of spread (change in width).

mass_flux: Flux/throughput of mass through this unit.

max_iteration_count: Count of maximum solution loop iterations before aborting.

orientation: Orientation of the roll pass for displaying purposes. Meaning of height and width always refer to standard horizontal orientation anyway. Commonly 0 (horizontal) or 90 (vertical) for two-roll passes. Other integer values are supported, too.

power: Total energy demand per time of this unit.

reappearing_cross_section: Cross-section of the roll pass witch appears again in the next roll-pass due to spreading.

rel_draught: Relative draught (change in height).

rel_elongation: Relative elongation (change in length).

rel_spread: Relative spread (change in width).

roll_force: Vertical roll force.

rotation: Rotation applied to the incoming profile in ° (degree) before entry in this roll pass. Alternatively, provide a boolean value: false equals 0, true means automatic determination from hook functions of Rotator.rotation.

spread: Coefficient of spread (change in width).

strain: Mean equivalent strain applied to the workpiece.

strain_rate: Mean equivalent strain rate.

surface_area: Surface area of workpiece within the unit.

target_cross_section_area: Target cross-section of the out profile.

target_cross_section_filling_ratio: Target cross-section filling ratio of the out profile.

target_filling_ratio: Target filling ratio of the out profile.

target_width: Target width of the out profile.

tip_cross_section: Cross-section of the roll pass at filling with its tip width.

tip_width: Width of the intersection of the extended groove flanks (theoretical maximum filling width).

usable_cross_section: Cross-section of the roll pass at ideal filling with its usable width.

usable_width: Usable width (width of ideal filling). Equals the usable width of the groove for two-roll passes, but deviates for three and four-roll passes.

velocity: Mean velocity of material flow.

volume: Volume of workpiece material within the unit.

volume_flux: Flux/throughput of volume through this unit.